New hope for gastric cancer patients

SINGAPORE - A significant finding by researchers here could lead to the development of different ways to treat gastric cancer, the fourth most lethal form of cancer in Singapore.

Gastric cancer is not one single cancer but a cluster of many different cancer types, some of which are triggered by bacteria or gastric inflammation, a team led by researchers from the Duke- NUS Graduate Medical School has found.

The finding could be the catalyst for new targeted ways to treat this form of cancer, which kills about 800,000 people globally each year and is the second most lethal cancer in the world after lung cancer.

The researchers studied cancer tissue from 203 patients and compared them with healthy tissue from some of the same patients.

In some of these gastric cancer types, some genes had undergone a process called methylation, which sometimes turns genes on or off without fundamentally changing them, and is linked to some known cancer risk factors such as bacterial infection with H. pylori, or inflammation.

The research team also found a subgroup of gastric cancers with extremely high levels of methylation, which make up about a third of all gastric cancer cases. These patients also tend to be younger and have poorer survival rates.

Associate Professor Patrick Tan, senior author of the research, said: "Our results provide further confirmation that gastric cancer is not one disease but a conglomerate of multiple diseases, each with different underlying biologies and hallmark features."

But in the lab, they found that the tumours with methylation-affected genes present in younger patients are more responsive to drugs that target methylation, and suggested this could be one avenue for new treatments.

Currently, patients are treated with a combination of surgery, drugs and radiotherapy.

Known methylation patterns could also be developed into a simple diagnostic test to detect gastric cancer at earlier stages in the disease, Prof Tan said.

The team's work was the first full survey determining which portions of specific genes are methylated in gastric cancer.

Previous studies had typically focused on individual genes.

Their work, funded by the Singapore Gastric Cancer Consortium and allied grants, was published in the journal Science Translational Medicine this week.